gdb cannot print vector as I hoped (resolved it's because of return value optimization by gcc)

inspect_var_rvo.txt

# In RVO, the compiler figures out the local instance of the object to be a return value, 
# the compiler allocates the instance directly in the caller context.
#
# See: http://demin.ws/blog/english/2012/04/14/return-vector-by-value-or-pointer/
#
$ g++ -g rvo.cc
rvo.cc: In member function 'std::vector<int, std::allocator<int> > Klass::Func(const std::vector<int, std::allocator<int> >&)':
rvo.cc:16: warning: conversion to 'int' from 'size_t' may alter its value
$ gdb -q a.out
Reading symbols from /work/tetsuo-s/cpp-sandbox/a.out...done.
(gdb) b Klass::Func
Breakpoint 1 at 0x4007a8: file rvo.cc, line 14.
(gdb) r
Starting program: /work/tetsuo-s/cpp-sandbox/a.out 

Breakpoint 1, Klass::Func (this=0x7fffffffd94e, v=std::vector of length 3, capacity 3 = {...}) at rvo.cc:14
14        vector<int> temp(v);
(gdb) n
15        for (size_t i = 0; i < v.size(); ++i) {
(gdb) p temp
$1 = std::vector of length 0, capacity -19
(gdb) up
#1  0x00000000004008ae in main () at rvo.cc:27
27        vector<int> ret = k.Func(v);
(gdb) p ret
$2 = std::vector of length 3, capacity 3 = {1, 2, -1}

rvo.txt

$ cat weird_vector.cc
#include <vector>

using namespace std;

class Klass {
 public:
  vector<int> Func(const vector<int>& v);
};

vector<int> Klass::Func(const vector<int>& v) {
  vector<int> temp(v);
  for (size_t i = 0; i < v.size(); ++i) {
    temp[i] -= i;
  }
  return temp;
}

int main() {
  vector<int> v(3);
  v[0] = 1;
  v[1] = 2;
  v[2] = -1;
  Klass k;
  vector<int> ret = k.Func(v);
  return 0;
}
$ g++ -g weird_vector.cc
$ gdb -q a.out 
(gdb) b Klass::Func
Breakpoint 1 at 0x100001277: file weird_vector.cc, line 11.
(gdb) r
Starting program: /Users/tetsuo-s/work/cpp-sandbox/a.out
Breakpoint 1, Klass::Func (this=0x7fff5fbff330, v=std::vector of length 3, capacity 3 = {...}) at weird_vector.cc:11
11        vector<int> temp(v);
(gdb) n
12        for (size_t i = 0; i < v.size(); ++i) {
(gdb) p temp
$1 = std::vector of length 0, capacity 0
(gdb)